3.5.2 OLTC control with PEV/DG voltage support

To address the hunting problem, presented in the previous case, the V2GQ is coordinated with the COC. Two case studies dealing with PEV/DG voltage support are carried out, as follows:

1. DG active power curtailment, without PEV and DG reactive power supports, that is, <sup>γ</sup> <sup>¼</sup> <sup>X</sup> chð Þ<sup>i</sup> ð Þ;<sup>t</sup> ; Po ið Þ ;<sup>t</sup> h i, where <sup>Q</sup>PEV o ið Þ ;<sup>t</sup> <sup>¼</sup> <sup>0</sup>, <sup>∀</sup><sup>i</sup> <sup>∈</sup>IPEV and Qo ið Þ;<sup>t</sup> <sup>¼</sup> <sup>0</sup>, <sup>∀</sup><sup>i</sup> <sup>∈</sup><sup>I</sup> DG

$$\text{12.PEV and DG reactive power dissipated, that is, } \chi = \left[ \mathbb{X}\_{\{ch\_{(i)}\}}, \mathbb{Q}\_{o(i,t)}^{\text{PEV}}, \mathbb{P}\_{o(i,t)}, \mathbb{Q}\_{o(i,t)} \right]^{-1}$$

Figure 13 demonstrates the performance of the coordination algorithm when the voltage support is merely achieved via the DG active power curtailment (i.e., the

Figure 13. Response of coordination algorithm, assuming DG active power curtailment.

distributed between the RTS cores for performing parallel computations. The RTS is used to perform a hardware-in-the-loop (HiL) realization, where a central control unit, emulated by a host computer running GAMs, exchanges real-time data with the test network modeled in the RTS. The sampling time used to realize the HiL

This section compares the responses of the conventional and COC controllers for

the OLTC. The voltage support from PEVs and DGs is disabled to study their

application is 100 μs.

Number of vehicles in the parking lots.

Research Trends and Challenges in Smart Grids

Figure 11.

Figure 12.

68

3.5.1 OLTC control without PEV/DG voltage support

OLTC response: (a & b) conventional control and (c & d) COC.

violations associated with DGs and PEVs: (i) centralized and (ii) distributed voltage regulation schemes. These schemes necessitate communication and, thus, may benefit from the communication infrastructure embedded within smart grids. The centralized approach employs state estimation and solves an optimization problem to dispatch DG reactive power for optimal voltage regulation. On the other hand, the distributed approach is an expert-based control or model-free approach, which coordinates a variety of voltage control devices with the goal of providing effective and nonoptimal voltage regulation with fewer communication requirements. Case studies for a centralized voltage control scheme illuminated the role of PEV and DG reactive powers in providing optimal voltage regulation with relaxed tap operation.

Voltage Regulation in Smart Grids

DOI: http://dx.doi.org/10.5772/intechopen.85108

Author details

University of Windsor, Windsor, Ontario, Canada

provided the original work is properly cited.

\*Address all correspondence to: mazzouz@uwindsor.ca

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Maher Azzouz

71

Figure 14. Response of coordination algorithm, activating both PEV and DG reactive power dispatch.

first case study). The coordination algorithm keeps the bus voltages within the standard limits, as shown in Figure 13(a). The hunting problem is avoided with a reasonable daily tap operation, that is, 16 taps/day; see Figure 13(b). Further, the required PEV charging demand is satisfied, as illustrated in Figure 13(c). However, 6.14% of the DG available energy is curtailed because the priority is given to supplying the PEV demand, as shown in Figure 13(d). This privilege is considered to comply with the distribution system code developed by the Ontario Energy Board [23]. It states that electric utilities should deliver the required energy to supply their loads (such as PEVs) unless there is a technical limit violation. The only solution to maximize the energy extraction is therefore to incorporate both the PEVs and DGs in the voltage support. Figure 14 illustrates the response of the coordination algorithm for the second case when PEV and DG reactive powers are employed for voltage regulation. Utilizing the full features of the V2GQ results in a proper voltage regulation using only 4 taps/day, extracting all DG power and charging all PEVs.
